Construction equipment utilizes power sources such as diesel engines to provide power to move the construction equipment from location to location and power the hydraulic and electrical systems thereon. The hydraulic system typically includes a hydraulic pump that is driven by the engine supplying pressurized hydraulic fluid drawn from a reservoir. The pressurized hydraulic fluid is directed by an operator using levers, pedals and/or joysticks. The control systems may include positional controls that are moved by the operator with the change in position of the control being electrically detected by sensing devices. The position of the controls is conveyed to a controller circuit. The controller circuit interprets the signals and provides controlling signals in the form of electrical current to electro-hydraulic valves so that the pressurized hydraulic fluid can be directed to a hydraulic cylinder as directed by the operator.
The amount of electrical current required to actuate a valve is dependent upon the characteristics of the valve and the variation of manufacturing tolerances of both the electrical actuation portion and the mechanical characteristics of the valve itself. For example, variations in the valve mechanism can alter the amount of physical force needed to actuate the valve. Additionally, electrical variables, such as the number of turns of a coil can vary somewhat from coil to coil thereby providing a variation in the operation of the valve. A proportional valve, which may be operated by a servomechanism or similar type device, may also vary from unit to unit thereby creating some uncertainty as to the amount of current necessary to actuate the valve.
What is needed in the art is a simple self-contained calibration method to functionally remove variability inherent with the construction of an electro-hydraulic valve.